Definition of juveniles:
(adj) :
Young; not fully developed.
(adj) :
Characteristic of youth or immaturity; childish.
(n) :
A person younger than the age of majority; a minor.
(n) :
A prepubescent child.
(n) :
(criminal law) A person younger than the age of full criminal responsibility, such that the person either cannot be held criminally liable or is subject to less severe forms of punishment.
(n) :
(zoology) A sexually immature animal.